Method and apparatus for continuously applying nanolaminate metal coatings

ABSTRACT

Described herein are apparatus and methods for the continuous application of nanolaminated materials by electrodeposition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 14/855,223, filed Sep. 15, 2015, which is a continuation of International Application No. PCT/US2014/031101, filed Mar. 18, 2014, which claims the benefit of U.S. Provisional Application No. 61/802,102, filed Mar. 15, 2013, each of which is incorporated by reference herein in its entirety.

BACKGROUND

Nanolaminate materials have become widely studied over the past several decades. As a result some desirable advanced performance characteristics of those materials have been discovered and their potential application in numerous fields recognized. While the potential application of nanolaminated materials in numerous areas, including civil infrastructure, automotive, aerospace, electronics, and other areas has been recognized, the materials are on the whole not available in substantial quantities due to the lack of a continuous process for their production.

SUMMARY

Described herein are apparatus and methods for the continuous application of nanolaminated materials by electrodeposition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a continuous processing apparatus for the application of nanolaminated coatings configured for conductive materials that can be rolled.

DETAILED DESCRIPTION 1.0 Definitions

“Electrolyte” as used herein means an electrolyte bath, plating bath, or electroplating solution from which one or more metals may be electroplated.

“Workpiece” means an elongated conductive material or loop of conductive material.

“Nanolaminate” or “nanolaminated” as used herein refers to materials or coatings that comprise a series of layers less than 1 micron.

All compositions given as percentages are given as percent by weight unless stated otherwise.

2.0 Electrodeposition Apparatus for Continuous Application of Nanolaminated Coatings

The continuous application of nanolaminate coatings on conductive materials can be accomplished using an electrodeposition apparatus comprising:

-   -   at least a first electrodeposition cell 1 through which a         conductive workpiece 2, which serves as an electrode in the         cell, is moved at a rate,     -   a rate control mechanism that controls the rate the workpiece is         moved through the electrodeposition cell;     -   an optional mixer for agitating electrolyte during the         electrodeposition process (shown schematically in FIG. 1 as item         3);     -   a counter electrode 4; and     -   a power supply 8 controlling the current density applied to the         workpiece in a time varying manner as it moves through the cell.

The rate control mechanism (throughput control mechanism) may be integral to one or more drive motors or the conveying system (e.g., rollers, wheels, pulleys, etc., of the apparatus), or housed in associated control equipment; accordingly, it is not shown in FIG. 1. Similarly the counter electrode may have a variety of configurations including, but not limited to, bars, plates, wires, baskets, rods, conformal anodes and the like, and accordingly is shown generically as a plate 4 at the bottom of the electrodeposition cell 1 in FIG. 1. The counter electrode, which functions as an anode except during reverse pulses, may be inert or may be active, in which case the anode will contain the metal species that is to be deposited and will dissolve into solution during operation.

Power supply 8 may control the current density in a variety of ways including applying two or more, three or more or four or more different average current densities to the workpiece as it moves through the electrodeposition cell. In one embodiment the power supply can control the current density in a time varying manner that includes applying an offset current, so that the workpiece remains cathodic when it is moved through the electrodeposition cell and the electrode remains anodic even though the potential between the workpiece and the electrode varies. In another embodiment the power supply varies the current density in a time varying manner which comprises varying one or more of: the maximum current, baseline current, minimum current, frequency, pulse current modulation and reverse pulse current modulation.

The workpiece may be introduced to the electrolyte by immersion in said electrolyte or by spray application of the electrolyte to the workpiece. The application of the electrolyte to the workpiece may be modulated. The rate by which the workpiece is moved through the electrolyte may also be modulated.

Mixing of electrolyte in the electrodeposition cell is provided by solution circulation, a mechanical mixer and/or ultrasonic agitators. While bulk mixing can be provided by the mixer 3, which can be controlled or configured to operate at variable speeds during the electrodeposition process, the apparatus may optionally include one or more ultrasonic agitators which are shown schematically as blocks 5 in the apparatus of FIG. 1. The ultrasonic agitators of the apparatus may be configured to operate independently in a continuous or in a non-continuous fashion (e.g., in a pulsed fashion). In one embodiment the ultrasonic agitators may operate at about 17.000 to 23,000 Hz. In another embodiment they may operate at about 20,000 Hz. Mixing of the electrolyte may also occur in a separate reservoir and the mixed electrolyte may contact the workpiece by immersion or by spray application. Instead of one or more salts of a metal to be electroplated, the electrolyte may comprise two or more, three or more or four or more different salts of electrodepositable metals.

The apparatus may include a location from which the workpiece material is supplied (e.g., a payoff reel) and a location where the coated workpiece is taken up (e.g., a take-up reel, which may be part of a strip puller for conveying a workpiece through the apparatus). Accordingly, the apparatus may comprise a first location 6, from which the workpiece is moved to the electrodeposition cell and/or a second location 7 for receiving the workpiece after it has moved through the electrodeposition cell. Location 6 and location 7 are shown as spindles with reels in FIG. 1, however, they may also consist of racks for storing lengths of materials, folding apparatus, and even enclosures with one or more small openings, from which a workpiece (e.g., a wire, cable, strip or ribbon) is withdrawn or into which a coated workpiece is inserted.

In one embodiment the first and/or second location comprises a spool or a spindle. In such an embodiment the apparatus may be configured to electrodeposit a nanolaminate coating on a continuum of connected parts, wire, rod, sheet or tube that can be wound on the spool or around the spindle.

The apparatus may further comprise an aqueous or a non-aqueous electrolyte. The electrolyte may comprise salts of two or more, three or more or four or more electrodepositable metals.

In addition to the above-mentioned components, the apparatus may comprise one or more locations for treatment of the workpiece prior or subsequent to electrodeposition. In one embodiment the apparatus further includes one or more locations, between the first location and the electrodeposition cell, where the workpiece is contacted with one or more of: a solvent, an acid, a base, an etchant, and/or a rinsing agent to remove the solvent, acid, base, or etchant. In another embodiment the apparatus further includes one or more locations between the electrodeposition cell and a second location, where the coated workpiece is subject to one or more of: cleaning with solvent, cleaning with acid, cleaning with base, passivation treatments and rinsing.

3.0 Electrodeposition Process for the Continuous Application of Nanolaminated Coatings on Workpieces

3.1 Workpieces

Workpieces may take a variety of forms or shapes. Workpieces may be, for example, in the form of wire, rod, tube, or sheet stock (e.g., rolls or folded sheets). Workpieces may be metal or other conductive strip, sheet or wire. Workpieces may also comprise a series of discrete parts that may be, for example, affixed to a sheet or webbing (e.g., metal netting or flexible screen) so as to form a sheet-like assembly that can be introduced into the electrodeposition cell in the same manner as substantially flat sheets that are to be coated with a nanolaminate by electrodeposition. Workpieces which am a series of discrete parts connected to form a strip must be connected by a conductive connector.

Virtually any material may be used as a workpiece, provided it can be rendered conductive and is not negatively affected by the electrolyte. The materials that may be employed as workpieces include, but are not limited to, metal, conductive polymers (e.g., polymers comprising polyaniline or polypyrrole), or non-conductive polymers rendered conductive by inclusion of conductive materials (e.g., metal powders, carbon black, graphene, graphite, carbon nanotubes, carbon nanofibers, or graphite fibers) or electroless application of a metal coating.

3.2 Continuous Electrodeposition of Nanolaminate Coatings

Nanolaminate coatings may be continuously electrodeposited by a method comprising:

-   -   moving a workpiece through an apparatus comprising at least a         first electrodeposition cell at a rate, where the         electrodeposition cell comprises an electrode and an electrolyte         comprising salts of one or more metals to be electrodeposited;         and     -   controlling the mixing rate and/or the current density applied         to the workpiece in a time varying manner as the workpiece moves         through the cell, thereby electrodepositing a nanolaminate         coating.

By controlling the current density applied to the workpiece in a time varying manner, nanolaminate coatings having layers varying in elemental composition and/or the microstructure of the electrodeposited material can be prepared. In one set of embodiments, controlling the current density in a time varying manner comprises applying two or more, three or more or four or more different current densities to the workpiece as it moves through the electrodeposition cell. In another embodiment, controlling the current density in a time varying manner includes applying an offset current, so that the workpiece remains cathodic when it is moved through the electrodeposition cell and the electrode remains anodic, even though the potential between the workpiece and the electrode varies in time to produce nanolamination. In another embodiment controlling the current density in a time varying manner comprises varying one or more of: the baseline current, pulse current modulation and reverse pulse current modulation.

Nanolaminated coatings may also be formed on the workpiece as it passes through the electrodeposition cell by controlling the mixing rate in a time varying manner. In one embodiment, controlling the mixing rate comprises agitating the electrolyte with a mixer (e.g., impeller or pump) at varying rates. In another embodiment, controlling the mixing rate comprises agitating the electrolyte by operating an ultrasonic agitator in a time varying manner (e.g., continuously, non-continuously, with a varying amplitude over time, or in a series of regular pulses of fixed amplitude). In another embodiment, controlling the mixing rate comprises pulsing a spray application of the electrolyte to the workpiece.

In another embodiment, the nanolaminate coatings may be formed by varying both the current density and the mixing rate simultaneously or alternately in the same electrodeposition process.

Regardless of which parameters are varied to induce nanolaminations in the coating applied to the workpiece as it is moved through the electrodeposition cell, the rate at which the workpiece passes through the cell represents another parameter that can be controlled. In one embodiment rates that can be employed are in a range of about 1 to about 300 feet per minute. In other embodiments, the rates that can be employed are greater than about 1, 5, 10, 30, 50, 100, 150, 200, 250 or 300 feet per minute, or from about 1 to about 30 feet per minute, about 30 to about 100 feet per minute, about 100 to about 200 feet per minute, about 200 to about 300 feet per minute, or more than about 300 feet per minute. Faster rates will alter the time any portion of the workpiece being plated remains in the electrodeposition cell. Accordingly, the rate of mass transfer (rate of electrodeposition) that must be achieved to deposit the same nanolaminate coating thickness varies with the rate the workpiece is moved through the cell. In addition, where processes employ variations in current density to achieve nanolamination, the rate the variation in current density occurs must also be increased with an increasing rate of workpiece movement through the electrodeposition cell.

In one embodiment, the electrodeposition process may further include a step of moving the workpiece from a first location to the electrodeposition cell. In another embodiment, the electrodeposition process may further include a step of moving the workpiece from the electrodeposition cell to a second location for receiving the workpiece after electrodeposition of the nanolaminate coating. As such, the method may further comprise both moving the workpiece from a first location to the electrodeposition cell and moving the workpiece from the electrodeposition cell to the second location.

3.3 Electrolytes and Nanolaminate Coating Compositions and Structures

Continuous electrodeposition of nanolaminate coatings can be conducted from either aqueous or non-aqueous electrolytes comprising salts of the metals to be electrodeposited.

In one embodiment, electrodepositing a nanolaminate coating comprises the electrodeposition of a layered composition comprising one or more, two or more, three or more or four or more different elements independently selected from Ag, Al, Au, Be, Co, Cr, Cu, Fe, Hg, In, Mg, Mn, Mo, Nb, Nd, Ni, P, Pd, Pt, Re, Rh, Sb, Sn, Pb, Ta, Ti, W. V, Zn and Zr, wherein each of said independently selected metals is present at greater than about 0.1, about 0.05, about 0.01, about 0.005 or about 0.001% by weight. In one such embodiment, electrodepositing a nanolaminate coating comprises electrodeposition of a layered composition comprising two or more different elements independently selected from Ag, Al, Au, Be, Co. Cr, Cu, Fe, Hg, In, Mg. Mn, Mo, Nb, Nd, Ni, P, Pd, Pt, Re. Rh. Sb, Sn, Pb, Ta, Ti, W. V, Zn and Zr, wherein each of said independently selected metals is present at greater than about 0.005 or about 0.001% by weight. In another such embodiment, electrodepositing a nanolaminate coating comprises the electrodeposition of layers comprising two or more different metals, where the two or more different metals comprise: Zn and Fe, Zn and Ni, Co and Ni, Ni and Fe Ni and Cr, Ni and Al, Cu and Zn, Cu and Sn, or a composition comprising Al and Ni and Co (AlNiCo). In any of those embodiments the nanolaminate coating may comprise at least one portion consisting of a plurality of layers, wherein each of said layers has a thickness in a range selected independently from: about 5 nm to about 250 nm, from about 5 nm to about 25 nm, from about 10 nm to about 30 nm, from about 30 nm to about 60 nm, from about 40 nm to about 80 nm, from about 75 nm to about 100 nm, from about 100 nm to about 120 nm, from about 120 nm to about 140 nm, from about 140 nm to about 180 nm, from about 180 nm to about 200 nm, from about 200 nm to about 225 nm, from about 220 nm to about 250 nm, or from about 150 nm to about 250 nm.

In another embodiment, the electrodeposited nanolaminate coating compositions comprise a plurality of first layers and second layers that differ in structure or composition. The first layers and second layers may have discrete or diffuse interfaces at the boundary between the layers. In addition, the first and second layers may be arranged as alternating first and second layers.

In embodiments where the electrodeposited nanolaminate coatings comprise a plurality of alternating first layers and second layers, those layers may comprise two or more, three or more, four or more, six or more, eight or more, ten or more, twenty or more, forty or more, fifty or more, 100 or more, 200 or more, 500 or more, 1.000 or more, 1.500 or more, 2.000 or more, 3,000 or more, 5,000 or more or 8,000 or more alternating first and second layers independently selected for each multilayer coating.

In one embodiment each first layer and each second layer comprises, consists essentially of, or consists of two, three, four or more elements independently selected from: Ag, Al, Au, Be, Co, Cr. Cu, Fe, Hg, In, Mg, Mn, Mo. Nb, Nd, Ni, P, Pd, Pt, Re, Rh, Sb, Sn, Pb, Ta, Ti, W, V, Zn and Zr. In another embodiment, each first layer and each second layer comprises, consists essentially of, or consists of two, three, four or more elements independently selected from: Ag, Al, Au, Co. Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Sb. Sn, Mn, Pb, Ta, Ti, W, V, and Zn. In another embodiment, each first layer and each second layer comprises, consists essentially of, or consists of two, three, four or more elements independently selected from: Al. Au, Co. Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Sn. Mn. Ti, W, V, and Zn.

In one embodiment each first layer comprises nickel in a range independently selected from about 1% to about 5%, about 5% to about 7%, about 7% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 30%, about 30% to about 40%, about 40% to about 50%, about 50% to about 55%, about 55% to about 60%, about 60% to about 65%, about 65% to about 70%, about 70% to about 75%, about 75% to about 80%, about 80% to about 85%, about 85% to about 90%, about 90% to about 92%, about 92% to about 93%, about 93% to about 94%, about 94% to about 95%, about 95% to about 96%, about 96% to about 97%, about 97% to about 98% or about 98% to about 99%. In such an embodiment, each second layer may comprise cobalt and/or chromium in a range independently selected from about 1% to about 35%, about 1% to about 3%, about 2% to about 5%, about 5% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 25%, about 25% to about 30% or about 30% to about 35%.

In one embodiment each first layer comprises nickel in a range independently selected from about 1% to about 5%, about 5% to about 7%, about 7% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 30%, about 30% to about 40%, about 40% to about 50%, about 50% to about 55%, about 55% to about 60%, about 60% to about 65%, about 65% to about 70%, about 70% to about 75%, about 75% to about 80%, about 80% to about 85%, about 85% to about 90%, about 90% to about 92%, about 92% to about 93%, about 93% to about 94%, about 94% to about 95%, about 95% to about 96%, about 96% to about 97%, about 97% to about 98% or about 98% to about 99%, and the balance of the layer comprises cobalt and/or chromium. In such an embodiment, each second layer may comprise cobalt and/or chromium in a range selected independently from about 1% to about 35%, about 1% to about 3%, about 2% to about 5%, about 5% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 25%, about 25% to about 30% or about 30% to about 35%, and the balance of the layer comprises nickel. In such embodiments, first and second layers may additionally comprise aluminum.

In one embodiment each first layer comprises nickel in a range independently selected from about 1% to about 5%, about 5% to about 7%, about 7% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 30%, about 30% to about 40%, about 40% to about 50%, about 50% to about 55%, about 55% to about 60%, about 60% to about 65%, about 65% to about 70%, about 70% to about 75%, about 75% to about 80%, about 80% to about 85%, about 85% to about 90%, about 90% to about 92%, about 92% to about 93%, about 93% to about 94%, about 94% to about 95%, about 95% to about 96%, about 96% to about 97%, about 97% to about 98% or about 98% to about 99%, and the balance of the layer comprises aluminum. In such an embodiment, each second layer may comprise aluminum in a range selected independently from about % to about 35%, about 1% to about 3%, about 2% to about 5%, about 5% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 25%, about 25% to about 30% or about 30% to about 35%, and the balance of the layer comprises nickel.

In one embodiment each first layer comprises nickel in a range independently selected from about 1% to about 5%, about 5% to about 7%, about 7% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 30%, about 30% to about 40%, about 40% to about 50%, about 50% to about 55%, about 55% to about 60%, about 60% to about 65%, about 65% to about 70%, about 70% to about 75%, about 75% to about 80%, about 80% to about 85%, about 85% to about 90%, about 90% to about 92%, about 92% to about 93%, about 93% to about 94%, about 94% to about 95%, about 95% to about 96%, about 96% to about 97%, about 97% to about 98% or about 98% to about 99%, and the balance of the layer comprises iron. In such an embodiment, each second layer may comprise iron in a range independently selected from about 1% to about 35%, about 1% to about 3%, about 2% to about 5%, about 5% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 25%, about 25% to about 30% or about 30% to about 35%, and the balance of the layer comprises nickel.

In one embodiment each first layer comprises zinc in a range independently selected from about 1% to about 5%, about 5% to about 7%, about 7% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 30%, about 30% to about 40%, about 40% to about 50%, about 50% to about 55%, about 55% to about 60%, about 60% to about 65%, about 65% to about 70%, about 70% to about 75%, about 75% to about 80%, about 80% to about 85%, about 85% to about 90%, about 90% to about 92%, about 92% to about 93%, about 93% to about 94%, about 94% to about 95%, about 95% to about 96%, about 96% to about 97%, about 97% to about 98%, about 98% to about 99%, about 99% to about 99.5%, about 99.2% to about 99.7%, or about 99.5% to about 99.99%, and the balance of the layer comprises iron. In such an embodiment, each second layer may comprise iron in a range independently selected from about 0.01% to about 35%, about 0.01% to about 0.5%, about 0.3% to about 0.8%, about 0.5% to about 1.0%, about 1% to about 3%, about 2% to about 5%, about 5% to about 10%, about 10% to about 15%, about 15% to about 20%, about 20% to about 25%, about 25% to about 30% or about 30% to about 35%, and the balance of the layer comprises zinc.

In any of the foregoing embodiments the first and/or second layers may each comprise one or more, two or more, three or more, or four or more elements selected independently for each first and second layer from the group consisting of Ag, Al. Au, Be, Co, Cr, Cu. Fe, Hg, In, Mg. Mn. Mo, Nb, Nd, Ni, P, Pd, Pt, Re, Rh, Sb, Sn. Pb, Ta, Ti, W. V. Zn and Zr.

3.4 Pre to about and Post-Electrodeposition Treatments

Prior to electrodeposition, or following electrodeposition, methods of continuously electrodepositing a nanolaminate coating may include further steps of pre-electrodeposition or post-electrodeposition treatment.

Accordingly, the apparatus described above may further comprise one or more locations between the first location and the electrodeposition cell, and the method may further comprise contacting the workpiece with one or more of: a solvent, an acid, a base, an etchant, or a rinsing solution (e.g., water) to remove said solvent, acid, base, or etchant. In addition, the apparatus described above may further comprise one or more locations between the electrodeposition cell and a second location, and the method may further comprise contacting the workpiece with one or more of: a solvent, an acid, a base, a passivation agent, or a rinse solution (e.g., water) to remove the solvent, acid, base or passivation agent.

4.0 Nanolaminated Articles Prepared by Continuous Electrodeposition

The process and apparatus described herein may be adapted for the preparation of articles comprising, consisting essentially of, or consisting of nanolaminated materials by the use of a workpiece to which the coating applied during electrodeposition does not adhere tightly. The article may be obtained after removal of the workpiece from the electrodeposition process by separating the coating from the workpiece. In addition, where the workpiece is not flat, 3-dimensional articles may be formed as reliefs on the contoured surface of the workpiece.

4.0 Certain Embodiments

1. An apparatus for electrodepositing a nanolaminate coating comprising:

at least a first electrodeposition cell (e.g., one or more, two or more, three or more, four or more electrodeposition cells) through which a conductive workpiece is moved at a rate,

a rate control mechanism that controls the rate the workpiece is moved through the electrodeposition cell(s);

each electrodeposition cell optionally comprising a mixer for agitating an electrolyte in its respective electrodeposition cell during the electrodeposition process;

each electrodeposition cell optionally comprising a flow control unit for applying an electrolyte to the workpiece;

an electrode; and

a power supply controlling the current density applied to the workpiece in a time varying manner as it moves through the cell(s).

2. The apparatus of embodiment 1, wherein controlling the current density in a time varying manner comprises applying two or more, three or more or four or more different current densities to the workpiece as it moves through the electrodeposition cell(s).

3. The apparatus of embodiment 2, wherein controlling the current density in a time varying manner comprises applying an offset current, so that the workpiece remains cathodic when it is moved through the electrodeposition cell(s) and the electrode remains anodic. 4. The apparatus of any of embodiments 1 or 2, wherein the time varying manner comprises one or more of varying the baseline current, pulse current modulation and reverse pulse current modulation. 5. The apparatus of any of the preceding embodiments, wherein one or more of the electrodeposition cell(s) further comprises an ultrasonic agitator. 6. The apparatus of embodiment 5, wherein each ultrasonic agitator independently operates continuously or in a pulsed fashion. 7. The apparatus of any of the preceding embodiments, wherein each mixer operates independently to variably mix an electrolyte placed in its respective electrodeposition cell(s). 8. The apparatus of any of the preceding embodiments, further comprising a first location, from which the workpiece is moved to the electrodeposition cell(s), and/or a second location, for receiving the workpiece after it has moved through one or more of the electrodeposition cell(s). 9. The apparatus of embodiment 8, wherein the first and/or second location comprises a spool or a spindle. 10. The apparatus of embodiment 9 wherein the workpiece is a wire, rod, sheet or tube that can be wound on said spool or around said spindle. 11. The apparatus of any of the preceding embodiments, wherein any one or more of said electrodeposition cell(s) comprises an aqueous electrolyte. 12. The apparatus of any of embodiments 1-10, wherein any one or more of said electrodeposition cell(s) comprises a non-aqueous electrolyte. 13. The apparatus of any preceding embodiment, wherein said electrolyte(s) comprises salts of two or more, three or more or four or more electrodepositable metals. 14. The apparatus of any of the preceding embodiments further comprising one or more locations between the first location and the electrodeposition cell(s), where the workpiece is contacted with one or more of: a solvent, an acid, a base, an etchant, and a rinsing agent to remove said solvent, acid, base, and/or etchant. 15. The apparatus of any of the preceding embodiments further comprising one or more locations between the electrodeposition cell(s) and said second location, where the coated workpiece is subject to one or more of: cleaning with solvent, cleaning with acid, cleaning with base, passivation treatments, and rinsing. 16. A method of electrodepositing a nanolaminate coating comprising:

moving a workpiece through an apparatus comprising at least a first electrodeposition cell (one, two, three, four, five, or more electrodeposition cell(s)) at a rate, where the electrodeposition cell(s) comprises an electrode and an electrolyte comprising salts of two or more, three or more, or four or more different electrodepositable metals; and

controlling the mixing rate and/or the current density applied to the workpiece in a time varying manner as it moves through the cell(s), thereby electrodepositing a nanolaminate coating.

17. The method of embodiment 16, wherein controlling the current density in a time varying manner comprises applying two or more, three or more, or four or more different current densities to the workpiece as it moves through the electrodeposition cell(s).

18. The method of embodiment 16 or 17, wherein controlling the current density in a time varying manner comprises applying an offset current, so that the workpiece remains cathodic when it is moved through the electrodeposition cell(s) and the electrode remains anodic. 19. The method of embodiments 16 or 17, wherein the time varying manner comprises one or more of: varying the baseline current, pulse current modulation and reverse pulse current modulation. 20. The method of any of embodiments 16-19, wherein one or more electrodeposition cell(s) optionally comprises a mixer, each of which mixer is independently operated at a single rate or at varying rates to agitate the electrolyte within its respective electrodeposition cell. 21. The method of any of embodiments 16-20, wherein one or more electrodeposition cell(s) optionally comprises an ultrasonic agitator, each of which is independently operated continuously or in a non-continuous fashion to control the mixing rate. 22. The method of any of embodiments 16-21, further comprising controlling the rate the workpiece is moved through the electrodeposition cell(s). 23. The method of any of embodiments 16-22, wherein the apparatus further comprises a first location, from which the workpiece is moved to the electrodeposition cell(s), and/or a second location for receiving the workpiece after it has moved through the electrodeposition cell(s), the method further comprising moving the workpiece from the first location to the electrodeposition cell(s) and/or moving the workpiece from the electrodeposition cell(s) to the second location. 24. The method of embodiment 23, wherein the apparatus further comprises one or more locations between the first location and the electrodeposition cell(s), and the method further comprises contacting the workpiece with one or more of: a solvent, an acid, a base, and an etchant, and rinsing to remove said solvent, acid, base, or etchant at one or more of the locations between the first location and the electrodeposition cell(s). 25. The method of embodiments 23 or 24, wherein the apparatus further comprises one or more locations between the electrodeposition cell(s) and said second location, and the method further comprises contacting the workpiece with one or more of: a solvent, an acid, a base, a passivation agent, and a rinsing agent to remove the solvent, acid base and/or passivation agent at one or more locations between the electrodeposition cell(s) and said second location. 26. The method of any of embodiments 16-25, wherein said workpiece is comprised of a metal, a conductive polymer or a non-conductive polymer rendered conductive by inclusion of conductive materials or electroless application of a metal. 27. The method of any of embodiments 16-26, wherein the workpiece is a wire, rod, sheet or tube. 28. The method of any of embodiments 16-27, wherein the electrolyte(s) is/are aqueous electrolyte(s). 29. The method of any of embodiments 16-27, wherein the electrolyte(s) is/are a non-aqueous electrolyte(s). 30. The method of any of embodiments 16-29, wherein electrodepositing a nanolaminate coating comprises the electrodeposition of a layered composition comprising one or more, two or more, three or more or four or more different elements independently selected from Ag, Al, Au, Be, Co, Cr, Cu, Fe, Hg, In, Mg, Mn, Mo, Nb, Nd, Ni, P, Pd, Pt, Re, Rh, Sb, Sn, Pb, Ta, Ti, W, V, Zn and Zr, wherein each of said independently selected metals is present at greater than 0.1, 0.05, 0.01, 0.005 or 0.001% by weight. 31. The method of any of embodiments 16-29, wherein electrodepositing a nanolaminate coating comprises the electrodeposition of a layered composition comprising two or more different elements independently selected from Ag, Al, Au, Be. Co, Cr, Cu, Fe, Hg, In, Mg, Mn, Mo, Nb, Nd, Ni, P. Pd, Pt. Re, Rh, Sb, Sn, Pb, Ta, Ti. W, V. Zn and Zr, wherein each of said independently selected metals is present at greater than about 0.1, 0.05, 0.01, 0.005 or 0.001% by weight. 32. The method of embodiment 31, wherein said two or more different metals comprise: Zn and Fe, Zn and Ni, Co and Ni, Ni and Fe, Ni and Cr, Ni and Al. Cu and Zn, Cu and Sn or a composition comprising Al and Ni and Co. 33. The method according to any of embodiments 16-32, wherein the nanolaminate coating comprises at least one portion consisting of a plurality of layers, wherein each of said layers has a thickness in a range selected independently from about 5 nm to about 250 nm, from about 5 nm to about 25 nm, from about 10 nm to about 30 nm, from about 30 nm to about 60 nm, from about 40 nm to about 80 nm, from about 75 nm to about 100 nm, from about 100 nm to about 120 nm, from about 120 nm to about 140 nm, from about 140 nm to about 180 nm, from about 180 nm to about 200 nm, from about 200 nm to about 225 nm, from about 220 nm to about 250 nm, or from about 150 nm to about 250 nm. 34. The method of any of embodiments 16-33, wherein the nanolaminate coating composition comprises a plurality of first layers and second layers that differ in structure or composition, and which may have discrete or diffuse interfaces between the first and second layers. 35. The method of embodiment 34 wherein the first and second layers are arranged as alternating first and second layers. 36. The method of embodiment 35, wherein said plurality of alternating first layers and second layers comprises two or more, three or more, four or more, six or more, eight or more, ten or more, twenty or more, forty or more, fifty or more, 100 or more, 200 or more, 500 or more, 1,000 or more, 1,500 or more, 2,000 or more, 4,000 or more, 6,000 or more, or 8,000 or more alternating first and second layers independently selected for each multilayer coating. 37. The method of any of embodiments 34-36, wherein each first layer comprises nickel in a range independently selected from 1%-5%, 5%-7%, 7%-10%, 10%-15%, 15%-20%, 20%-30%, 30%-40%, 40%-50%, 50%-55%, 55%-60%, 60%-65%, 65%-70%, 70%-75%, 75%-80%, 80%-85%, 85%-90%, 90%-92%, 92%-93%, 93%-94%, 94%-95%, 95%-96%, 96%-97%, 97%-98% or 98%-99%. 38. The method of embodiment 37, wherein each second layer comprises cobalt and/or chromium in a range independently selected from 1%-35%, 1%-3%, 2%-5%, 5%-10%, 10%-15%, 15%-20%, 20%-25%, 25%-30% or 30%-35%. 39. The method of any of embodiments 34-36, wherein each first layer comprises nickel in a range independently selected from 1%-5%, 5%-7%, 7%-10%, 10%-15%, 15%-20%, 20%-30%, 30%-40%, 40%-50%, 50%-55%, 55%-60%, 60%-65%, 65%-70%, 70%-75%, 75%-80%, 80%-85%, 85%-90%, 90%-92%, 92%-93%, 93%-94%, 94%-95%, 95%-96%, 96%-97%, 97%-98% or 98%-99%, and the balance of the layer is cobalt and/or chromium. 40. The method of embodiment 39, wherein each second layer comprises cobalt and/or chromium in a range selected independently from 1%-35%, %-3%, 2%-5%, 5%-10%, 10%-15%, 15%-20%, 20%-25%, 25%-30% or 30%-35%, and the balance of the layer is nickel. 41. The method of any of embodiments 34-36, wherein each first layer comprises nickel in a range independently selected from 1%-5%, 5%-7%, 7%-10%, 10%-15%, 15%-20%, 20%-30%, 30%-40%, 40%-50%, 50%-55%, 55%-60%, 60%-65%, 65%-70%, 70%-75%, 75%-80%, 80%-85%, 85%-90%, 90%-92%, 92%-93%, 93%-94%, 94%-95%, 95%-96%, 96%-97%, 97%-98% or 98%-99%, and the balance of the layer comprises iron. 42. The method of embodiment 41, wherein each second layer comprises iron in a range independently selected from 1%-35%. 1%-3%, 2%-5%, 5%-10%, 10%-15%, 15%-20%, 20%-25%, 25%-30% or 30%-35%, and the balance of the layer comprises nickel. 43. The method of any of embodiments 34-36, wherein each first layer comprises zinc in a range independently selected from 1%-5%, 5%-7%, 7%-10%, 10%-15%, 15%-20%, 20%-30%, 30%-40%, 40%-50%, 50%-55%, 55%-60%, 60%-65%, 65%-70%, 70%-75%, 75%-80%, 80%-85%, 85%-90%, 90%-92%, 92%-93%, 93%-94%, 94%-95%, 95%-96%, 96%-97%, 97%-98%, 98%-99%, 99%-99.5%, 99.2%-99.7%, or 99.5%-99.99%, and the balance of the layer comprises iron. 44. The method of embodiment 43, wherein each second layer comprises iron in a range independently selected from 0.01%-35%, 0.01%-0.5%, 0.3%-0.8%, 0.5%-1.0%, 1%-3%, 2%-5%, 5%-10%, 10%-15%, 15%-20%, 20%-25%, 25%-30% or 30%-35%, and the balance of the layer comprises zinc. 45. The method of any of embodiments 34-36, wherein one or more of said first and/or second layers comprises one or more, two or more, three or more or four or more elements selected independently for each first and second layer from the group consisting of Ag, Al, Au, C, Cr, Cu, Fe, Mg, Mn, Mo. Sb, Si, Sn, Pb, Ta, Ti, W, V, Zn and Zr. 46. A product produced by the method of any of embodiments 16-44. 

The invention claimed is:
 1. A method comprising: moving a workpiece through an electrodeposition cell of an apparatus at a rate, the electrodeposition cell comprising an electrode and an electrolyte comprising salts of at least two metals; and electrodepositing a nanolaminate coating on the workpiece by applying a time varying potential between the workpiece and the electrode, and repeatedly applying three or more different current densities of an offset current to the workpiece as it moves through the electrodeposition cell during the applied time varying potential, the offset current being such that the workpiece remains cathodic as it is moved through the electrodeposition cell and the electrode remains anodic.
 2. The method of claim 1, wherein the apparatus comprises a plurality of rotating elements in the electrodeposition cell, the plurality of rotating elements being arranged such that the workpiece travels in a serpentine path guided by the plurality of rotating elements.
 3. The method of claim 1, wherein the three or more different current densities of the offset current are applied by a power supply that controls the current applied to the workpiece.
 4. The method of claim 1, wherein the workpiece is a sheet.
 5. The method of claim 1, wherein the at least two metals are selected from silver (Ag), aluminum (Al), gold (Au), beryllium (Be), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), indium (In), magnesium (Mg), manganese (Mn), molybdenum (Mo), niobium (Nb), neodymium (Nd), nickel (Ni), palladium (Pd), platinum (Pt), rhenium (Re), rhodium (Rh), antimony (Sb), tin (Sn), lead (Pb), (Ta), titanium (Ti), tungsten (W), vanadium (V), zinc (Zn), and zirconium (Zr).
 6. The method of claim 1, wherein the electrolyte is an aqueous electrolyte.
 7. The method of claim 1, wherein the electrolyte is a non-aqueous electrolyte.
 8. The method of claim 1, further comprising moving the workpiece from a first storage location in which an uncoated portion of the workpiece is stored to the electrodeposition cell.
 9. The method of claim 8, further comprising moving the workpiece from the electrodeposition cell to a second storage location in which a coated portion of the workpiece is stored.
 10. The method of claim 1, wherein the electrodepositing the nanolaminate coating further comprises agitating the electrolyte.
 11. The method of claim 10, wherein the electrolyte is agitated by an ultrasonic agitator.
 12. The method of claim 1, wherein each layer of the nanolaminate coating comprises: Zn and Fe; Zn and Ni; Co and Ni; Ni and Fe; Ni and Cr; Ni and Al; Cu and Zn; Cu and Sn; or Al, Ni, and Co.
 13. The method of claim 1, each layer of the nanolaminate coating has a thickness ranging from 5 nanometers to 250 nanometers.
 14. The method of claim 1, wherein the nanolaminate coating comprises a plurality of alternating first and second layers.
 15. The method of claim 14, wherein the plurality of alternating first and second layers comprises at least 10 alternating first and second layers.
 16. The method of claim 14, wherein the plurality of alternating first and second layers comprises at least 50 alternating first and second layers.
 17. The method of claim 14, wherein each layer of the nanolaminate coating comprises: Zn and Fe; Zn and Ni; Co and Ni; Ni and Fe; Ni and Cr; Ni and Al; Cu and Zn; Cu and Sn; or Al, Ni, and Co.
 18. The method of claim 14, wherein each layer of the nanolaminate coating comprises Zn and Fe.
 19. The method of claim 14, wherein each of the first layers comprises Zn in the range of 1%-99.99% by weight, and the balance of each of the first layers comprises Fe.
 20. The method of claim 14, wherein each of the second layers comprises Fe in the range of 0.01%-35% by weight, and the balance of each of the second layers comprises Zn. 